Device for laboratorical measuring of liquids



April 4, 1939. 1. szf-zcsl. 2,153,105

DEVICE FOR LABORATORICAL MEASURING OF LIQUIDS Filed` Feb. 27, 1956 S26/cs z' Patented Apr. 4, 1939 UNITED STATES PATENT OFFICE DEVICE FORLABORATORICAL MEASURING F LIQUIDS Istvn Szcsi, Budapest, Hungary 8Claims.

The invention relates to controlling devices, for use mainly inlaboratories, for measuring or dispensing very small quantities ofliquids with extreme accuracy.

One object of the invention is to ensure the possibility of easyhandling of the controlling apparatus.

Another object of the invention is to render the controlling apparatussuitable for a plurality of measurements or dispensing operationsdilering from each other for the simultaneous handling of a series oftubes for the distribution of liquids by aid of a controlling device.

The other details of the invention will appea in the course of thespecication. f

The drawing diagrammatically illustrates several embodiments of theinvention, shown by way of example for medical purposes.

Fig. 1 is a longitudinal section and partly in side elevation ofapparatus for the transference and xing of levels of liquid.

Fig. 2 illustrates a similar apparatus together with a complete pipette.This apparatus is provided with two auxiliary junctions.

Fig. 3 is a section taken along line III--III of Fig. 2, showing thecross-section of an auxiliary junction of the threaded type.

Fig. 4' illustrates apparatus similar to that shown in Fig. l, butprovided with an auxiliary membranepump and an abutment for the rubberball.

Fig. 5 shows, partly in longitudinal section and partly in sideelevation, apparatus of the type comprising two membrane pumps, theapparatus being tted with a pipette of the type usually employed for thecounting of blood cells.

Fig. 6 is a front elevation drawn to a smaller scale than that of theother figures, of apparatus of the type comprising a series of pipettesand a stand.

Up to now, the liquid to be examined has been drawn up into the pipettesby mouth or by means of a rubber ball iitted directly on the pipettes.This method is detrimental to health, and is also unreliable, because itis impossible even for a person possessing a great deal of practice toregulate the level of the liquid in an accurate manner.

By means of the invention, these drawbacks are eliminated by employingmeasuring tubes having a self-sealing bottom in communication with apump device ior displacing the liquid therein and having precision meansfor adjusting and precisely fixing the level of the liquid. The bottomsof the tubes are made self-sealing by providing an opening therein whichis so narrow that when the upper opening of the tube is closed, it isimpossible for the liquid contained in the tube to drip out merely byits own weight. Such apparatus is shown in Fig. l, where the-constituentparts of the apparatus are the casing I, a valve operated by means of ascrew-thread, namely the needle-valve 2, the hand-wheel 3, the tubejunction 4 and the junction 5 for the pump device comprising a rubberball 6, by means of which it is possible to produce either pressure orsuction. The pipette 'l is connected up to the tube junction 4 by meansof a rubber sleeve 8.

If the ball 6 exerts a suction effect and the lower end of the pipette'l reaches down into the liquid to be examined, all that is necessary inorder that the liquid should rise to the desired graduation is to effectan opening or closing of the needle-valve 2 by turning the hand-wheel 3.When the liquid is sucked up by the mouth or by means of a ball fitteddirectly to the pipette, it is not possible to close the upper space ofthe pipette in an air-tight manner, without thereby altering theconditions of pressure ruling in the space above the indicating level.It is also necessary to supervise, simultaneously, the variations of thelevel and the variations of the pressure, and it is not possible withsuch an arrangement to discontinue the pressure immediately when thedesired level is reached. The present invention enables the pressure tobe varied and the level to be xed as far as possible independently. Bymeans of the hand-ball or other pump devices it is easily possible'toproduce a continuous suction since it is possible to close the valve bya reflex motion and rapidly. The attention oi the operator may beconcentrated on observing the variation of the level alone, andaccordingly it is possible to work with such a degree of accuracy thatthe level may be varied at will, from one graduation to another. Whenclosing the valve the hand of the operator becomes released and thelevel remains unchanged, even if the lower end of the pipette is liftedout of the liquid to be examined. Thus, by the apparatus according tothe invention, the level existing at any moment will not only beadjusted, but will also be fixed at the same time.

If on the other hand, a pressure higher than atmospheric is produced inthe ball, it is necessary to proceed in the same way, in order todisfpense the desired quantity of liquid from the pipette in an accuratemanner. For dispensing in this manner, it has been necessary, up to now,to employ tubes tted with a cock on their lower ends. Such cocks, whichare usually of glass, in-

cating and render the dispensing operation tedious. All these drawbacksare eliminated by the invention, and, with an accurate adjustment of thevalve, dispensing in any quantities desired, and even accuratelymeasured uniform drops may be released from the pipette,

The tube junction 4 and the junction 5 for the pump device, betweenwhich two parts the valve 2 is inserted, are parallel, whereby handlingis simplified. For the same purpose the hand-wheel 3 is arranged so asto be in easy reach of the hand gripping .the mechanism, and thehand-wheel is sufliciently large to act as a base for the entireapparatus whereby the apparatus may be placed on a table with the wheeldownwards.

Figs. 2 and 4 illustrate apparatus which is substantially similar to thedevice shown in Fig. l. The differences are the following:

According to Fig. 2, a stufng box I0 `is provided on the casing I, abovethe tube junction 4. An opening 9 provides communication between theinterior of the tube junction 4 and the exterion of the casing throughthe stuffing box. The stufling box is adapted to receive a pipe 3l shownin Fig. 6, hereinafter more particularly described. When a pipette isattached to the sleeve 8 so as to enable the apparatus to operateupwardly from below, it is necessary to close the opening 9 and for thispurpose a rod II is inserted in the stufng box as shown in Fig. 2. Onthe other hand, when the apparatus is required to be employed in themanner shown in Fig. 6, the rod II is replaced by the pipe 3i and thetube junction 4 is closed.V By means of the construction shown in Fig.2, it is possible to employ the same apparatus in the manner shown inFig. 2 as well as in the manner shown in Fig. 6.

Above the valve 2, a screw-threaded nipple having an opening I2 isprovided which serves for assisting the rubber ball B. The nipple isprovided with an axially extending slot I3 having a depth equal to thatof the screw threads. This slot I3 is also shown in Fig. 3. The openingI2 is closed by a screw-cap I4. As soon as the screwcap I4 is slightlyopened, the space above the valve 2, together with the rubber ball 6,will immediately, through the slot I3, communicate with the atmosphere.The screw-cap I4 is opened when effecting the operation of liberatinguid drop by drop or for instance when it is desired to effect repeatedsuction by means of the rubber ball 6 after its first inflation, withvalve 2 in the closed position.

According to Fig. 4 the rubber ball 6 is iitted with an abutment shieldi5 and it is against this shield that the ball is pressed in order toenable it to be completely evacuated easily. On the side of the casing Ion which the tube junction 4 is situated, and above the valve 2, anadditional pump I6 is provided, serving as an auxiliary source ofpressure, its purpose being that in the closed condition of valve 2, itis still possible to control the liquid level with micrometricprecision. The resilient membrane pump I6, forming the additional pumpmay be regulated by means of the screw I'I. By these means it ispossible to compensate for variations of the liquid level resulting fromchanges of temperature taking place during operation.

According to Fig. 5 the means for varying the level of the liquid, andfixing it at the same time consists of two pumps of different size, eachof which has its own separate suction-pressure member and each of whichhas its own separate crease the cost of the apparatus, requirelubrimechanical regulator, the neness of the adjustment produced by thetwo regulators being different. Apparatus of such a type is usuallyemployed for a pipette i8 of bottle-gourd form, in order to make itpossible to conform even to the greatest differences of calibrationoccurring in immediate mutual succession. Thus for instance in the caseof the pipette I8 for the examination of blood the thin blood-drawingtube provides a space the volume of which exceeds a hundred times thevolume of the blood-drawing tube.

Two membrane pumps of different type are shown each of which has its ownindividual resilient membrane I9, 2li, and each of which has its ownindividual regulating screw 2I, 22, the said screws producing adjustmentof different degree of neness. The smaller pump is employed for thecontents of the narrow tube of the pipette I8, while the larger pump isemployed for the contents of the wide head part of the pipette I8. Thusit becomes possible to work with the same rapidity and accuracy in bothparts of the pipette.

The pumps are held together in a rigid manner by means of the frame 23,so that the adjustment of the levels of liquid will not vary even incase the apparatus is pressed by the operators hand.

The'regulator of the one pump is within easy reach of the hand whichoperates the other pump, so as to enable the apparatus to be held and atthe same time be regulated by hand. For this purpose one pump isarranged so that its spindle is inclined relatively to that of the otherpump.

According to Fig. 6, the device by which the level of the liquid isvaried, consists of the collecting tube 24 which is of substantialconstruction to prevent any deformation at the pressures occurringduring the operation of the device, and a series of tube junctions 25branching out from the collecting tube. This device is based on therecognition of the fact that automatic pressure distribution is, betweenthe limits coming under consideration, practically perfect. A device forvarying the liquid level in this type of apparatus comprises a closingmember and it is even possible to use an ordinary handball as a sourceof pressure for it. Inaccuracies of the ball, which would not bepermissible in the case of individual tubes, will become of no eiectowing to the fact that their inaccuracy becomes distributed over tentubes.

If the zero lines or the Calibrating base lines of the measuring ordispensing tubes connected to the common collecting tube are adjustedinto a common horizontal level, the distribution of pressure will beaccurate even in the case of tubes of different types. The accuracywhich can be attained even permits of only one or a number of thecontrol tubes being calibrated, while the others may remainuncalibrated. It is also sufcient if the adjustment of the levels ischecked in one or two control tubes only. Thus measurements are renderedmore rapid and the cost of the apparatus is substantially diminished.

Among the ten pipettes shown in the drawing which are connected to thetube junctions 25 there is only one calibrated pipette 'I, while thepipettes 25, 2l are uncalibrated. The diameter of the pipette 21 differsfrom that of the others, so that it is possible for a measured quantitydifferent from the measured quantities of the other pipettes to bedispensed from the pipette 2l. On

the bottom of one of the pipettes an extension 28 in the form oi aneedleis provided. 4Such extensions are used, when filling ampoules. y

The measuring apparatus together with all that belongs to it, issupported on the stand"29. The series of pipettes are held together bythe strap 30. i

To the collecting tube 24 there is connected the pipe 3l, which likewisekeeps its `shape unchanged at the service pressures occurring therein.The apparatus illustrated at 32 is of the kind described in connectionwith Fig. `2, by which the level of liquid is varied by measuredamounts, and at the same time fixed. Owing to this connection theaccuracy which has been assured in any case by the employment of thecollecting tube 24 is substantially increased.

What I claim is:

1. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination, a measuring tube, a casing, aflexible connection between the casing and the upper end of themeasuring tube for connecting and establishing open communicationbetween the casing and the measuring tube, a bulb depending from and inopen communication with the casing for drawing liquid into and expellingit from the measuring tube, a shield depending from said casing andinterposed between the bulb and the flexible connection and a precisionvalve in the casing between the bulb and the measuring tube, saidprecision valve having manual actuating means therefor arranged inproximity to the bulb so as to enable the bulb and the precision valveto be actuated by the same hand for adjusting and precisely xing theliquid level in the measuring tube.

2. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected tol said measuring tubefor varying the pressure in the interior of the tube to draw fluid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged so as to be actuatable by the hand actuating the pumpfor adjusting and precisely fixing the liquid level in the measuringtube, and an additional pump in open communication with the measuringtube and interposed between the precision valve and the measuring tubefor displacing the liquid to enable the liquid level in the measuringtube toi be varied when the precision valve is closed.

3. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor Varying the pressure in the interior of the tube to draw fluid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged so as to: be actuatable by the hand actuating the pumpfor adjusting and precisely fixing the liquid level in the measuringtube and a manually actuatable pump connected to the measuring tube andinterposed between the precision valve and the measuring tube fordisplacing the liquid to enable the liquid level in the measuring tubeto be varied when the precision valve is closed.

4. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor varying the pressure in the interior of the tube to draw iluid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arrangedA so as to be actuatable yby the hand actuating thepump for adjusting and precisely fixing the liquid level in themeasuring tube and a plurality of manually actuatable pumps of differentsize connected to the measuring tube and interposed between theprecision valve and the measuring tube for displacing the liquid toenable the liquid level in the measuring tube to be varied withdifferent degrees of iineness after the precision valve is closed.

5. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor varying the pressure in the interior of the tube to draw fluid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged soy as to be actuatable by the hand actuating the pumpfor adjusting and precisely xing the liquid level in the measuring tube,and a plurality of manually actuatable pumps of diierent size connectedto the measuring tube and interposed between the precision valve and themeasuring tube, each of said pumps having a separate adjusting member,the individual adjusting members being adapted to vary the adjustment ofthe respective pumps with a different degree of neness for displacingthe liquid to enable the liquid level in the measuring tube to be variedwith different degrees of fineness after the precision valve is closed.

6. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor varying the pressure in the interior of the tube to draw fluid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged so` as to be actuatable by the hand actuating the pumpfor adjusting and precisely fixing the liquid level in the measuringtube, and a plurality of manually actuatable diaphragm pumps ofdifferent size connected to the measuring tube and interposed betweenthe precision valve and the measuring tube for displacing the liquid toenable the liquid level in the measuring tube to be varied withdifferent degrees of iineness after the precision valve is closed.

7. Apparatus for measuring very small quantities of liquids with extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor varying the pressure in the interior of the tube to draw fluid intoand expel it from the measuring tube, a precision Valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged so as to be actuatable by the hand actuating the pumpfor adjusting and precisely fixing the liquid level in the measuringtube and a plurality of manually actuatable diaphragm pumps of differentsize connected to the measuring tube and interposed between theprecision valve and the measuring tube, each of said diaphragm pumpshaving a separate adjusting member, the individual adjusting membersbeing adapted to vary the adjustment of the respective diaphragm pumpswith a different degree of fineness ior displacing the liquid level inthe measuring tube to be varied With different degrees of iineness afterthe precision valve is closed.

8. Apparatus for measuring Very small quantities of liquids With extremeaccuracy, comprising in combination a measuring tube having a capillarylower end, a manually actuatable pump connected to said measuring tubefor varying the pressure in the interior of the tube to draw iiuid intoand expel it from the measuring tube, a precision valve interposedbetween said pump and the measuring tube and having actuating meanstherefor arranged so as to be actuatable by the hand actuating the pumpfor adjusting and precisely iixing the liquid level in the measuringtube, a plurality of manually actuatable pumps of diierent sizeconnected to the measuring tube and interposed between the precisionValve and the measuring tube, each of said pumps having a separateadjusting member, the individual adjusting members being adapted to varythe adjustment of the respective pumps with a different degree of nenessfor displacing the liquid in the measuring tube to enable the liquidlevel to be Varied with different degrees of iineness after theprecision valve is closed, the said adjusting members being located inproximity to one another so as to enable the actuation of the differentadjusting members to be eected with one hand.

ISTVN sZCsI.

